Glossary · Design
Galvo
A design in which the laser head stands still and two small, very fast mirrors steer the beam across the material. This is many times faster than a moving head.
Explained in more detail
A galvo scanner consists of two mirrors on galvanometer motors, one steering in X and one in Y. Because only the light mirrors move, marking speeds of several thousand mm/s are possible, and hobby devices often quote 3000 to 10,000 mm/s. An F-theta lens keeps the focus in one plane across the whole field. This limits the work area, typically 100 × 100 mm to 300 × 300 mm, as larger fields mean a larger focus spot. Galvos are standard on fibre lasers and are increasingly found on diode and CO₂ machines too.
Where does the term come from?
Galvo is short for galvanometer, a measuring instrument in which a coil in a magnetic field turns a pointer. The name goes back to the Italian physician Luigi Galvani. In the scanner, the same technology turns a mirror instead of a pointer.
In practice
- Allow for the work area: anything larger than the galvo field has to be processed in sections and joined.
- At the edge of the field the beam becomes more oblique and the spot somewhat larger. It is better to place important details in the centre.
- Galvo machines are hardly suitable for cutting thick wood; their strength is marking and engraving small parts.
- The height of the workpiece must match the focal length exactly; many machines show the focus with two red dots that meet.
Not to be confused
Do not confuse it with the gantry, where the whole head travels on axes. Gantry machines are slower but have a much larger work area.
Frequently asked questions
Is a galvo laser better than a gantry laser?
It is faster for small engravings and marks, but limited to a small field. For large sheets and cuts, a gantry machine makes more sense.
How large is the work area of a galvo laser?
That depends on the lens, often 110 × 110 mm. Larger lenses extend the field but enlarge the focal spot and reduce the energy density.